A bone plate is a hard, normally metallic plate that is configured for attachment to bone surfaces, across bone fragments or across areas of bone reconstruction. The bone plate is used to provide stability to those areas and may further be used to compress and immobilize those areas so as to facilitate rebuilding and mending of the bones. Typically, a bone plate is an elongated strip with a number of openings located at regular intervals for attachment of the bone plate to a bone using bone screws. The surfaces of the strip may be contoured, textured or otherwise formed to facilitate secure placement on a bone surface.
Some bone plates, such as compression plates, are positioned tightly against the outer surface of the bone. Accordingly, to provide proper distribution of loads between the bone and the bone plate, the bone plate should be closely conformed to the bone contours. The contours of the bones to which bone plates are attached, however, vary from individual to individual. Accordingly, maintaining an inventory of bone plates which are specially formed for an individual or even a group of individuals is cost prohibitive.
One type of bone plate that has been developed in response to problem of providing a bone plate that is properly shaped, is a reconstruction bar. Reconstruction bars are formed from a biocompatible material that can be bent using special tools during a surgery. Typically, the surgeon forms by hand a thin metal template of the specific bone contour at the desired implantation cite. This process is generally performed after an incision has been made to expose the implantation location and the metal template is physically placed against the patient's bone.
Once a template is formed, the surgeon uses the special tools to shape the reconstruction bar to visually match the metal template. A number of tools have been developed to assist in reshaping the bone plates. The tools include are bending irons, specially adapted pliers, and bench-mounted bending presses that will bend a plate between a pair of anvils, one anvil having a single contact point, and the opposite anvil having a spaced pair of contact points. The shaped reconstruction bar is then attached to the bone using bone screws. Therefore, in addition to the expense of the special tools, this process can be time consuming and require a high level of skill to achieve an acceptably shaped bone plate.
Moreover, the shaped bone plate will generally not conform exactly to the surface of the bone at the attachment location. Thus, tightening of the bone plate against the bone with the bone screws induces bending preloads on the bone plate resulting in spring-back due to the resilient properties of the bone plate. Additionally, gaps may be present between the bone plate and the bone resulting in an uneven transfer of load from the plate to the bone. Consequently, the bone screw may break or strip away from the bone resulting in loss of fracture reduction, bone misalignment, extended healing time or corrective surgeries.
Therefore, a need exists for a bone plate that can easily be conformed to the shape of a patient's bone. A further need exists for a bone plate that does not require a large number of special tools and which is easy to manufacture.